Road oils



Patented Oct. 27, 1936 UNITED. STATES PATENT OFFICE ROAD oms ration of Indiana 1 Application December 29, 1932, Serial No. 649,430

5 Claims. (CL 196-22) This invention relates to road oils, and it pertains more particularly to the process of treating road oils to improve their desirable characteristics.

Road oils must conform to very strict specifications, prescribed by State highway departments for oils used on public roads. Usually these oils must contain at least 6% of material insoluble in hexane, they must not contain more than a predetermined amount of volatile matter, they must have a minimum percentage of material insoluble in carbon disulfide, they must yield a certain content of 100 F. melting point residue, and the asphaltic residue must have a high ductility. It is often diificult, if not impossible, to meet road oil specifications by merely fractionating the crude mixed base or asphaltic base petroleum oil, and it is likewise difficult or impossible to meet the road oil specifications with fractions or blends of pressure tar" (tar obtainedbycracking. polymerizing, or hydrogenating petroleum products to form gasoline, etc.) The object of my invention is to provide a means for treating pressure tar or similar carbonaceous materials obtained from petroleum whereby it can be made to meet the rigorous road oil specifications. More particularly, the object is to increase the hexane insoluble material of road oil without materially affecting its other characteristics. I accomplish the desired result by lightly chlorlnating the road oil with a gas in which the chlorine is diluted and in which the amount of chlorine is maintained within critical limits. Heretofore it has been generally supposed that the addition of chlorine to liquid hydrocarbons of this sort would result in the formation of a sludge and grainy carbon-like particles which would separate from the oil. It was believed that the chlorination would raise the carbon dlsulfide insoluble content to a very considerable extent. I have discovered that when small amounts of chlorine diluted with air are added in small quantities at comparatively low temperatures to road oils, the hexane insoluble content thereof is raised very materially without materially affecting the other properties. I have discovered that it is important to control the amount of chlorine employed to give the maximum hexane insoluble material. The percentage of hexane insoluble material can be increased about 65% to 10% by the use of critical amounts of chlorinebetween 0.05% to0.1% and 1.0%, themaximum effectiveness being obtained by the use of about 0.4%. The results obtained are decidedly unexpected from two points of view; first,'that minute quantities of chlorine sulfide. Furthermore, the product is quite noncorrosive,-and can be stored in iron containers for long periods of time without attack on the metal.

The invention will be more clearly understood from the followingdetailed description and from the accompanying drawing which forms a part of this specification and in which- Figure 1 represents diagrammatically an elevation of my chlorination system; I

Figure '2 is a graph showing the effect of the amount of chlorine added on the amount of hexane insoluble material produced; and

Figure 3 is a graph showing the effect of added chlorine on the viscosity of the road oil.

I will describe my invention as applied to a road oil prepared from pressure tar obtained from the cracking of Mid-Continent gas oil. This pressure tar has a hexane insoluble content of 3.8%, an evaporation toss of 6.7%, an asphalt content of 44.0%, a furol viscosity at 77 F. of 86 seconds,

and a carbon dlsulfide soluble content of 99.8%. It should be understood, however, that the invention is applicable to road oils of widely varying characteristics and from varying sources, parjticularly road oils which are deficient in the per- 1 centage of hexane insoluble material.

The road oil can be stored in a suitable storage tank i0 and heated by means of steam coils M to a temperature of about 150 F. to about 180 F. Although this is the preferred temperature for my treatment, the chlorination can be done at any reasonable temperature from 80-300" F., as long as the chlorine is sumcientiy diluted, as will be hereinafter described.

Chlorine gas from high pressure cylinder it is metered through valve it and mixed with about ten volumes of air from storage tank it. The air may be compressed by compressor it and it may be metered through valve it to line Il'i, wherein it is mixed with chlorine. The dilute chlorine is conducted by pipe ii to an injector or diffuser,-

such as perforated plpe i8, and an amount of chlorine gas is blown into the road oil equal to about 0.4% by'weight thereof. The relative proportions of chlorine and diluent gas are not critical and will depend somewhat on the temperatures employed. At high diiutions there may be an objectionable loss of unreacted chlorine and at low dilutions there may be an immediate formation of insoluble matter at the locus of the chlorine bubble. Previous attempts at straight chlorination have probably resulted in sludge formation because the concentration of the chlorine was too high at the temperatures employed or because too much chlorine was employed. The reaction of the chlorine is a vigorous one and even at a 1-10 dilution, no free chlorine is round in the exit gases. However, large quantities 01' hydrogen sulfide and hydrogen chloride are given of! through vent it. The finished product may be withdrawn from feed line 20 after the above described reaction.

The precise amount of chlorine and the exact dilution can be varied somewhat with difi'erent road oils, but one skilled in the art can base the reaction on the preferred embodiment hereinabove described.

By adding dilute chlorine gas in small increments in the manner hereinabove described I have found that the percentage of hexane insoluble material varies as shown in Figure 2 and that for this particular stoclr the optimum results are obtained by the use of 0.4% of chlorine (by weight). In Figure 3 I have shown the eifect of the added chlorine on viscosity. It appears that no other characteristic of the road oil is materially changed; the evaporation loss, asphalt content and amount of material soluble in carbon disulfide all check the original untreated road 011 within the limits of experimental error.

I have described the use of air as a diluent but it should be understood that I can use other ases for this purpose. I prefer to use an oxidizlng gas because I believe it supplements the action of the chlorine. I prefer to use about 10 volumes of air per volume of chlorine but I can use from one to twenty.voiumes or even larger amounts under various operating conditions and with various road oils. A simple test will show whether or not the concentration of chlorine is suillciently high to cause sludge formation and sufficient diluent should be used to avoid sludging. I

While I have described in detail a preferred embodiment of my invention it should be understood that I do not limit myself to said details except as defined by the following claims, which should be construed as broadly as the prior art will permit.

I claim:

1. The method of treating pressure tar to convert it into a satisiactory road oil which comprises contacting said pressure tar at a temperature 01' about F. to about 300 F. with from about 0.05% to about 1.0% of its weight of chicrine gas, said chlorine gas being diluted with at least about an equal volume of a diluent gas such as air, whereby the hexane insoluble content of said pressure tar is increased without materially afl'ecting the other properties thereof.

2. The method of treating pressure tar to convert it into a satisfactory road oil which comprises contacting said pressure tar at a temperature of about F. to about 180 F. with from about 0.05% to about 1.0% of its weight 01 chlorine gas, said chlorine gas being diluted with at least about an equal volume of a diluent gas such as air, whereby the hexane insoluble content of said pressure tar is increased without materially aflecting the other properties thereof.

3. The methodof treating pressure tar to convert it into satisfactory road all which comprises injecting a dilute chlorine gas into a body of said pressure tar maintained at a temperature of about 80 F. to about 300 F'., the chlorine gas being diluted with at least about an equal volume 01 air, the total amount of chlorine being limited to about 0.05% to about 1.0% by weight based on said pressure tar, whereby the hexane insoluble content or" said pressure tar is increased without materially affecting the other properties thereof.

4. The method of treating pressure tar to convert itinto a satisfactory road oil which comprises injecting dilute chlorine gas into a body of said pressure tar maintained at a temperature of about 80 F. to about 300 FL, the chlorine gas being diluted with about 1 to about 20 volumes of a diluent gas such as air, the total amount oi chlorine being limited. to about 0.1 to about 1.0% by weight based on said pressure tar, whereby the hexane insoluble content of the pressure tar is increased Without materially affecting the other properties thereof. I

5. The method of treating pressure tar to convert it into a satisfactory road oil which com prises imecting dilute chlorine gas into a body of said pressure tar maintained at a temperature oi about 80 F. to about 300 F'.. the chlorine gas being diluted with about 1 to about 20 volumes of a diluent gas such as air, the total amount of chlorine being limited to about 0.4% by weight based on said pressure tar, whereby the hexane insoluble content of said pressure tar is increased without materially aflecting the other properties 59 thereof.

JOSEPH W. SPARKS. 

